Pencil



Patented May 18 1943 PENCIL Isidor Chesler, Oceanport, N. J assignor to Eagle Pencil Company, New York, N. Y., a corporation of Delaware Application January '1, 1941, Serial No. 373,406

Claims.

The present invention is applicable to pencils generally, the writing rods of which are of the non-calcined type and is especially advantageous when applied to copying or indellible pencils.

The rods of non-calcined lead pencils generally are commonly made of comminuted clay and pigment or other coloring matter, held together by a binder of water soluble material, such for instance,-as gum tragacanth, gum arabic or etherized cellulose, wholly or partly soluble in water.

In the process of assembling pencils of the above type, some of the water from the glue bonding the wooden sheath in place, will be absorbed in the lead rod, making it necessary to dry the assembled pencils as for instance by storing them for sufficient time in a dry room to allow such water to evaporate, as otherwise the lead rod will be materially weakened and the life of the pencil curtailed. In rods of the copying or indellible type, the coloring medium comprises large proportions of water soluble dye, generally aniline dye'which is hygroscopic. As a consequence, water from the glue not only enters the rod as in the case of non-calcined leads generally, but it dissolves some of the dye from the rod, with resultant staining of the surrounding sheath. In hot or humid climates such for instance, as in certain parts of South America.

and in the tropics where copying lead pencils are widely used, the hygroscopic lead rod will take on considerable moisture and will be weakened by swelling, with possible splitting also of the wood sheath, so that the useful life of the pencil is shortened.

It is among the objects of the invention to provide a pencil of the non-calcined type'and 'a method of fabricating the same by which no weakening of the lead rod is incurred, but on the contrary the rod is strengthened,'even though drying or heat treating the assembled pencil is dispensed with.

Another object is to provide a copying pencil of the above type of prolonged shelf life and usefulness, by which the common precaution of storing such pencils in a cooldry place is dispensed with and the pencil maintains its maximum life and efliciency and no swelling of the lead rod occurs, even though the pencil be left in a hot and humid climate for long periods of time.

According to the invention, the otherwise conventional lead rod is enclosed in a waterproof jacket, intimately bonded therewith and capable of being water-wetted, which will prevent egress of the water soluble ingredients from the lead rod or entry of water or water soluble ingredients into the lead rod, and will form an anchoring base for the water soluble glue by which the lead is secured within the wooden or other sheath therefor.

The conventional lead rod of the non-calcined type is made from a dough of comminuted clay admixed with coloring matter, and with a suitable water soluble binder, which dough is extruded through an appropriate die to make the rods. The binder is usually of the water soluble type, of gum trag'acanth, gum arabic or etherized cellulose or similar materials, wholly or partly soluble in water. For the crayon type of lead, a suitable pigment is used as the coloring matter. For the copying type of lead rod, a

'water solubledye, usually aniline dye in powdered form is used in lieu of or in combination with pigment.

According to the invention, the conventional lead rods of the crayon or of the copying type as above set forth, are encased in'a jacket, composed of resin, preferably incorporating metal her which is characterized by high waterproof qualities. This may be'diluted with other less costly resin, such as alkyd or urea formaldehyde resin. Fifteen parts by weight of the resin, to one part of the metal powder is desirable.

The jacket is preferably applied by dipping the leads in a solution of the waterproof jacket composition. Desirably the resin is dissolved in a suitable volatile organic solvent such as toluol and the metal is dispersed in the solution. While the proportions of the ingredients may be varied widely, it is preferred to use approximately ten parts by weight of chlorinated rubber to 5 parts of synthetic resin, the whole dissolved in four parts of toluol, with the addition of one part of the aluminum powder. A specific formula which has been used to great advantage is the following:

Chlorinated rubber per cent by weight 51.25 Synthetic resin (7 parts dissolved in 3 parts of mineral spirits such as kerosene The leads are desirably dipped into the tank containing the waterproof jacket composition,

the leads being gripped near their upper ends in a board covered with a rubber mat containing holes to fit the leads,

After dipping the rods in the bath set forth, the same are lifted out by withdrawing at the rate of about four inches per minute. This permits flaky aluminum particles dispersed in the solution to conform, shingle fashion over the surface of the rod. The leads after withdrawal are permitted to dry and then desirably subjected to a second like dipping and upon drying are ready to be assembled in conventional manner into the wooden sheath.

In the accompanying drawing in which is shownone of various possible embodiments of the several features of the invention,

Fig. 1 is a perspective view with parts broken away showing the structure of the pencil incor porating the invention,

Fig. 2 is a cross-sectional view on a larger scale on line 22 of Fig. 1, and

Fig. 3 is a perspective view'of the lead rod as an article of manufacture.

In the drawing, the rod appears at H), the jacket of resin withthe metal particles appears at H, and is shown partly broken away, the two sections of the wooden sheath are shown at I! and I3, and the glue bonding the elements together at M.

Thelead rod, jacketed as set forth, may be stored indefinitely prior to assembly, without any danger of injury thereto even in a humid and hot environment. In the case of copying pencils, the dye will under no circumstances leak or exude therefrom, the bright or silvery appearance of the jacket being maintained throughout.

In the assembled pencil, the waterproof jacket H prevents any water from the glue ll entering the core of the lead rod l0, so that the latter Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A'pencil 'of the non-calcined type having water soluble binder and color ingredients in the form of a rod, a sheath comprising sections, water soluble glue bondingsaid sections to one another and to the rod and a substantially waterproof jacket encasing the rod and interposed between the rod and the glue bonded sheath.

2 A lead pencil comprising a rod of the noncalcined type having water soluble dye incorporated therein, a waterproof water-wettable jacket about said rod and a sheath adhesively bonded about said Jacket by water soluble glue.

3. A lead pencil of the copying type, comprising a rod made of clay, water soluble dye of hygroscopic character and water soluble binder, a waterproof water-wettable jacket about said rod, a sheath thereabout and water soluble glu bonding the latter about said waterproof jacket.

4. A lead pencil of the copying type, having a rod of clay and water soluble binder with hygroscopic water soluble dye incorporated therein, a

does not become weakened. Likewise, inthe case of the copying lead, water from the glue is excludedfrom the core by the waterproof jacket H and the aniline dye will not discolor the wooden sheath. Since the water is effectively excluded from the core of the lead, the hygroscopic aniline dye cannot take on any extraneous moisture and the objections to swelling are obviated. The metal particles lying in shingle fashion along the waterproof coating, contribute to sealing of the same even though the resin under change of .temperature may develop minute fissures or contributes to the mechanical strength of the .lead which renders the use of such coated lead particularly advantageous in mechanical pencils. As many changes could be made in the above construction and method and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

jacket thereabout, composed of approximately 15 parts by weight of synthetic resin, admixed with one part of flaky aluminum powden-and a'sheath about said rod having a water soluble glue bond with respect to said jacket.

5. A waterproof writing rod for a lead pencil, comprising a rod length made up of clay, water soluble binder and incorporated coloring matter therein, a waterproof jacket thereover, comprising a mixture of resin and metal powder and intimately bonded about the rod.

6. A waterproof writing rod for a copying pencil', comprising a rod length made up of clay, water soluble binder and aniline dye, a waterproof jacket thereover comprising a mixture of resin and flaky aluminum powder intimately bonded about the rod 7. A waterproof writing rod for lead pencils, comprising a rod length made up of clay, water soluble binder and incorporating a hygroscopic dye, and a waterproof'jacket thereover comprising a mixture of resin and flaky aluminum particles lodged shingle fashion along the surface of the jacket. .8.' A lead pencil of the copying type comprising a rod made of clay, water soluble dye of hygroscopic character and water soluble binder, a waterproof, water-wettable jacket about said rod, said jacket including chlorinated rubber ingredient, a sheath thereabout and water soluble glue bonding the latter aboutsaid waterproof jacket.

9. A waterproof writing rod for a copying pencil, comprising a rod length made up of clay,

water soluble binder and incorporating a hygro-' scopic dye and a waterproof jacket thereover comprising a mixture of chlorinated rubber and synthetic resin.

10. A waterproof writing rod for a copying pencil, comprising a rod length made up of clay, water soluble binder and incorporating a hygroscopic dye and a waterproof jacket thereover comprising a mixture of chlorinated rubber and synthetic resin, and flaky aluminum particles lodged shingle fashion along the surface of the jacket.

ISIDOR CHESLER. 

